1. Field of the Invention
The present invention relates to a process for recovering 1,3-dimethyl-2-imidazolidinone.
2. Prior Art
1,3-Dimethyl-2-imidazolidinone is an aprotic polar solvent with excellent acid- and alkaline-resistance, and is frequently used as a solvent for various kind of organic synthetic reactions (ex. JP-A-6-192156, JP-A-11-12253, JP-A-2002-121186, JP-A-2002-293766, JP-A-2003306487 and JP-A-11-152272). Hereinafter 1,3-dimethyl-2-imidazolidinone may also be referred to as DMI.
The objective compounds in the reactions are taken out, for example, by a method adding water and a water-insoluble organic solvent to the reaction mixture and extracting, a method adding water to the reaction mixture and crystallizing, and the like.
As DMI is very highly soluble in water, DMI is usually distributed in water layer and aqueous solution containing DMI in the case that water is used in the aftertreatment of the reaction as described above. From the industrial and environmental view, it is desired that DMI is recovered and reused from the aqueous solution without abandonment of the solution.
As a method recovering DMI from aqueous solution containing DMI described above, a method adding caustic alkali to the solution is known. However, after the recovery of DMI, the alkali solution generated should be neutralized before discarding.